Every star dies, but not every would-be star really lives.
“The origin and evolution of life are connected in the most intimate way with the origin and evolution of the stars.” –Carl Sagan
Supernovae may be the most spectacular cosmic explosions, but planetary nebulae are hundreds of times as numerous.
When they run out of nuclear fuel, Sun-like stars blow off their outer layers and contract into a central white dwarf.
The outer nebula consists of hydrogen, blown off first, while the white dwarf is mostly carbon and oxygen.
The white dwarf is small, but hot enough to evaporate the cold, neutral gas clumps surrounding it.
These evaporating gas globules are too small to form new stars, and instead return their material to the interstellar medium.
The Helix nebula has a disk-like and bubble-like structure to it, formed by the dying central star.
An infrared view highlights the neutral, cold gas.
All of it will evaporate over time, while the central star is so hot it barely shows up at these cold wavelengths.
In the ultraviolet, however, the hot, reflected starlight is visible everywhere.
The infrared and ultraviolet together showcase the tenuous, gaseous details that are lost in the optical.
A multiwavelength view is required to reveal the full suite of structure here.
Eventually, all the external material will return to the galaxy, enabling new generations of stars to form.
Mostly Mute Monday tells the story of an astronomical entity, event, or phenomenon in visuals and no more than 200 words.Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.